Myujth

I have 2 docs posts and postDrafts. In some point I want to publish the document from the postDraft into post.
The content is something like body: "blah blah".

So the trivial solution is to pull the postDraft content and then send back to posts document. Here is my code for that.

 export const publishDraftById = (postId) => async dispatch => 
 return new Promise((resolve, reject) => 
 postDraftsRef.doc(postId).get()
 .then(doc => 
 if (!doc.exists) 
 reject('No such document!');
 else 
 const draft = doc.data();
 postsRef.doc(postId).update(
 body: draft.body,
 date_modified: new Date()
 );
 resolve();
 
 )
 .catch((err) => 
 reject(err);
 console.log('Error getting documents', err);
 );
 )
 ;

But what I really think can be helpful is a way to do something like this meta code

"assign posts(postid).body = postDraft(postid).body"

Can I somehow approach this?

Is there a way to copy doc value into another one without pulling the data and sending back

No, there is not. You need to get the document first in order to be able to write it back. There is no way to simply get a property within a document and write it within another document without doing this. There are no field-level permissions or access to a document. It's the entire document, or nothing.

So if you want to read a field {body: "blah blah", then you will get the entire document and not only the property that you have write it to another document. So there are two operation involved, a read and a write operation.